Flashbang

Ever wondered how far away a lightning strike is? FlashBang tells you
instantly - no counting, no mental arithmetic. It's a lightning distance
calculator that lives in your browser toolbar, ready the moment the sky
lights up.

HOW IT WORKS
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Tap the button the moment you see lightning. Tap again when you hear
the thunder. FlashBang calculates the distance using the speed of sound,
adjusted for actual air temperature - more accurate than the basic
"divide by 5" rule.

FEATURES
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⚡ One-button operation - tap to see, tap to hear
📍 Optional live weather - auto-fetches local temperature for accurate
sound speed calculation (warmer air = faster sound = shorter distance)
📏 Results in both km and miles
↓↑ Trend indicators - see if the storm is approaching or moving away
⚠ Safety alert when a storm is within 5 km / 3 miles and closing
🕐 Session history with individual entry delete (corrects a mistimed tap)
🗑 Auto-clears after 48 hours

THE SCIENCE
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This thunder distance calculator uses the formula v = 331.3 + (0.606 × T°C)
rather than a fixed speed - because sound travels measurably faster in
warm air than cold. At 8°C it moves at ~336 m/s; at 30°C it's ~349 m/s.
Over a 10-second gap that's a real difference.

Also known as the flash-to-bang method - the same technique used by
meteorologists, outdoor safety professionals, and sports event managers
to assess storm proximity. FlashBang puts it in your browser toolbar as
a proper storm distance tool, ready when you need it.

"Bolts from the blue" - strikes from apparently clear sky up to 10 miles
from a storm - are rare but real. If you can hear thunder, you are within
striking distance. When in doubt, seek shelter.

No data collected. No account required. Works entirely in your browser.